How Persistent Is Armed Conflict?
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How persistent is armed conflict?∗ James D. Fearon and David D. Laitin Department of Political Science Stanford University March 14, 2013 Abstract We assess the degree of persistence in armed conflict in particular places over the last two centuries, asking in addition if conflict-ridden places have durable features – social, demographic or geographical – that explain persistence, or whether armed conflict at one time has a causal effect on propensity for armed conflict at later times. For all types of war in the Correlates of War data, we code the territories on which the armed conflict occurred. The data reveal significant levels of persistence in territories that experienced extra-state (imperial and colonial) and non-state wars in an earlier era. Exogenous features such as geography and pre-1800 demography are important in explaining where conflicts persist. However there remains significant persistence controlling for geographic and demographic features. In particular, extra-state wars before 1945 are strongly related to civil war after 1945. This persistence does not appear to arise from the long-run enmity of particular groups that fight repeatedly over centuries. We conjecture that imperial and colonial wars may have been more likely in territories where there were more and/or more developed pre-colonial state structures, and that either the persistence of these structures or changes in them brought about by the violent encounters raised civil war risks after 1945. 1 Introduction Do civil wars ever end? Given that we now have a large literature on how civil wars end and what determines peace duration after a war’s end, this may seem like an odd question.1 And certainly if one uses the ∗Data and analysis for this project were first presented at the XVIth World Economic History Congress, 9-13 July 2012, Stellenbosch, South Africa. This version was prepared for presentation at the Annual Meeting of the American Political Science Association, New Orleans, Louisiana, August 29-September 2, 2012. Thanks to Keegan Boyar, Megan Costello, Kolby Hanson, and Carrie Lee for excellent research assistance. This paper is a draft; comments are welcome. 1A few examples, though very far from a thorough list, include Walter (2002), Fortna (2008), Hartzell and Hoddie 1 coding criteria that scholars working in this area typically use – considering, for example, a war to be terminated if violence ends for some period of time like three months, a year, or two years – then not only do civil wars end, but many “end” repeatedly! For instance, the Correlates of War (COW) project codes six distinct, terminated wars in Angola since 1945, four of whose “ends” are separated from the start of the next war by just over a year, and the fifth by less than five years. Was that six wars, or one long stretch of quite persistent armed conflict? In this paper we consider what can be learned by asking about how persistent armed conflict has been in particular places over a long period of time, roughly the last two centuries. Economists studying economic growth have found remarkable historical persistence in a variety of measures of political and economic institutions (for a review see Nunn 2009). Is it also the case that certain places are highly conflict prone and have been this way for a long time? If this is the case, is it because they have durable features, social or geographical, that have favored armed conflict for at least the last 200 years, or is it that armed conflict at one time has a causal effect on propensity for armed conflict at later times?2 Up to (non-trivial) limits of existing conflict data and some additions we have made to them, we are able to answer the first, descriptive question fairly well. There is indeed a moderate amount of historical persistence in armed conflict through time. We use the most recent update of the Correlates of War (COW) war lists,which cover the period from 1816 to 2007.3 We ask how does fighting in all or certain kinds of armed conflict before 1945 (or in robustness checks, the larger of 1945 and year of independence) correlate with fighting on the same territory after 1945. The types of COW conflicts considered are inter-, intra-, extra-, and non-state wars.4 We use as our geo- (2007), Kreutz (2010), Licklider (1995), DeRouen and Bercovitch (2008), Balch-Lindsay and Enterline (2000), and Fearon (2004). 2DeRouen and Bercovitch (2008) note that many post-1945 conflicts are highly persistent. 3See Sarkees and Wayman (2010), although we use updates from December 2011 posted at http://www.correlatesofwar.org/. 4These are all defined relative to COW’s coding of official “interstate system members.” An interstate war is a war between two such states. An extrastate war is a war between one member state and some entity with organized forces that is not a recognized system member. An intrastate war is a civil war within a system member, and a non-state war 2 graphical units present-day state boundaries, for theoretical and practical reasons discussed below. We coded the 653 unique COW wars of all types for where the fighting took place, identifying 789 current country locales for fighting in the 653 conflicts. We find that doubling the number of war years prior to 1945 (the median is 3 and the mean is 7) associates on average with about a one-third increase in years of conflict within the same boundaries after 1945. The raw correlation of logged pre-45 war years with logged post-45 war years is .38, rising slightly to .42 if interstate wars are omitted.5 Further, we find no evidence that experience with interstate war or intrastate war before 1945 predicts post-1945 war experience. However, years of extrastate war before 1945 – that is, colonial and imperial war – is a strong predictor of war years after 1945 (which is mainly civil war). These relationships are strengthened when one considers only non-Western countries. On our second set of questions about the reasons for historical persistence – how much is it that durable factors make particular locales conflict prone, versus how much does armed conflict cause either more or less conflict in later periods – we make less progress. This is not surprising, given that we can’t conduct experiments and there are no obvious natural experiments that involve random assignment of pre-1945 conflict levels. But we can identify durable factors that plausibly cause conflict (or peace) before and after 1945, and see how controlling for these factors affects the correlation between conflict before and after 1945. Here we find that the correlation between pre-45 and post-45 conflict diminishes signifi- cantly, though it is not eliminated, when one controls for population estimates for the 1500s, and/or the degree of mountainousness of the territory. These are both factors that may favor armed conflict is a war between two non-system member political entities. COW defines system membership as follows (from the website): “Prior to 1920, the entity must have had a population greater than 500,000 and have had diplomatic missions at or above the rank of charge´ d’affaires with Britain and France. After 1920, the entity must be a member of the League of Nations or the United Nations, or have a population greater than 500,000 and receive diplomatic missions from two major powers.” 5Because total war years is highly skewed – many countries have zero, and a few have dozens or more – we add one and log our war years measures throughout the paper. Although it is not very natural to treat total war years as a count variable, doing so and using negative binomial regressions tends to strengthen the results reported here. 3 or be correlated with omitted variables favoring conflict, in both periods.6 The relationship is not much affected by controlling for a measure of ethnic diversity at the start of the colonial period, which is unrelated to conflict before 1945 (controlling for population) and positively related after.7 Our conjecture is that inter- and intrastate war before 1945 can be a sign of state building in progress (that would reduce the probability of persistence), or of factors such as the construction of historical grievances (that would dispose a country to continued conflict). Thus the net correlation with post-1945 conflict comes to nothing. By contrast, colonial/imperial and non-state wars before 1945 may indicate either (a) the existence of a plethora of precolonial authorities and structures that make for greater divisions and conflict among groups within post-colonial boundaries, or (b) the destruction of such authorities and structures by the colonizers, making post-colonial state-building more difficult. In both cases, the net correlation with post-1945 conflict would be positive. On this conjecture, consider the difference between Latin America and Africa. We count for each country whether it has experienced above or below the median number of war years for each of the two eras we are comparing. For the 33 Latin America/Caribbean countries, five of them had above the median in the first era with below the median in the second. These include Haiti, Mexico, Venezuela, Brazil, and Uruguay. None had the reverse experience. Seventy-four percent were above the world median in the earlier era; none of those 74% were above the median in war years post 1944. We suggest that the inter- and intra-state wars in the 19th century in Latin America and the Caribbean had state-building effects that on balance reduced their susceptibility to subsequent civil wars. Meanwhile, for the 49 African countries, while five moved from above median in the first era to below median in the second, seventeen territories were below the median in the first era 6As discussed below, population may be mechanically related to war years via the threshold of 1000 total killed necessary for entry into the COW data set.